Automatic telephone system



Nov. 9 1926 1,606,446 A. J. RAY

AUTOMATIC TELEPHONE SYSTEM Filed Auggt 16. 1924 H- mranlur- PatentedNov. 9, 1926.

(UNITED STATES:

1, 06,4 6 PATENT OFFICE.-

ARTHUB J.- RAY, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A. CORPORATION OF DELA-warm.

AUTOMATIC TELEPHONE SYSTEM;

Application filed August 16, 1924. Serial No. 732,360.

This invention relates in general to automatic telephone systems in.which connections are established through the mediumof subscribercontrolled automatic switches, but is more particularly concernedwithsuch automatic systems as include party hues and selective ringingequipment at the exchange.

In the patent toRay and Obergfell, No. 1,469,809, there is described asystem for selectively signalling twice the number of stations on aparty line as there are different kinds of ringlng current at theexchange, by means of a frequency selector individual to a connector,and a line reversing relay in said connector. The calling subscriber, bymanipulating his dial in accordance with the frequenc selecting digit,operates the frequency se ecting switch at the exchange to select thefrequency of ringing current which corresponds to the called substation,and to close a circuit for the reversing relay in case the substation ison the side of the line opposite that normally connected for ringing.

The principal object of the present invention is to provide a selectivesignalling system of the general type described above which is adaptedto signal twice the number of stations on a party line as there aredifferent kinds of ringing current at the ex change, without, however,requiring the line reversing relay, but by utilizing both wipers of thefrequency selecting switch for the selection of the proper ringingcurrents.

Another feature of the invention is the elimination of a relay which inthe Ray and Obergfell system is used to complete the ringing circuitafter the frequency selecting switch has operated. By suitablyrearranging the circuits it has been found possible to make the usualbusy test relay complete the ringing circuit at the proper time andaccordingly the relay heretofore used for this purpose has been doneaway with.

The means by which the foregoi-n objects, together with others not specically mentioned at this time, are accomplished will be fully set forthhereinafter, reference being had to the accompanying drawing, in whichis shown suflicient of the apparatus in an automatic telephone system toenable the invention to be explained and under stood. The referencecharacter A indicates an automatic substation of the usual type,

which has the usual talking instrumentahties and the calling device Sfor controlling the central office switches.

Substation A is connected with the central exchange by line conductors11 and 12 which terminate in the individual line or other similar lineswitches, is indicated in the drawing by the rectangle D. Inasmuch asselector switches are well knownin the art, it has not been considerednecessary to show the circuits in detail. It may be stated briefly thatthe selector D isa Strowger vertical and rotary switch of well knownmechanical construction, and operable according to the two-wire systemof control. When used in setting up a connection the selector respondsto the first digit in the called number in order to select adesiredgroup of connector switches, afterwhich the selector automaticallyrotates to select and connect with a trunk line extending to an idleconnector in the selected group. The above is, of course, true only of aone thousand line system; if the capacity of the system is greater thanthis, second or third selectors will be interposed between the firstselectors and connectors in the Well understood manner. This is theusual percentage trunking system, however, and need not be discussed indetail.

One of the trunk lines which the selector 1D has access to is shown inthe drawing as extending to the connector E, which is also a Strowgervertical and rotary switch having a capacity of one hundred subscriberslines.- The connector E is operable according to the two-wire system ofcontrol, like the selector D, and it responds to the next twodigits in acalled number to complete the connection to-the called line.

One of the lines to which the connector E has access is shown at theupper right hand corner of the drawing and comprises line conductors 101and 102. This line is a party line, and substations AA ,inclusive,

only one of which is shown completely, are connected in bridge of theline in the usual manner. The line switch C is associated with the partyline at the exchange, and is. 5 similar to the line switch C. Just belowthe connector E is shown an auxiliary switch which is indicated byreference character F. This is the switch referred to in the foregoing,andwhen used in the present situation is generally called a frequencyselecting switch. It comprises: briefly, the wipers 122 and 123,associated sets of bank contacts, the stepping magnet 120, and therelease magnet 121. The frequency selector F is individual to theconnector E. The improved circuit arrangement whereby the two switchescan operatein selectively signalling any one of the ten stations on theparty line shown, or another similar party line, is the principalsubject matter of the invention and will now be described.

For this purpose it will be assumed that the subscriber at substation Adesires to establish connection with a subscriber at sta- I lay 15closes a circuit at its armature 20,

which includes the winding of the switching relay 14 and the steppingmagnet 16 in,

series; and at its armature 21 connects the test wiper 26 to the abovecircuit at a point midway between the said switching relay and themagnet. The operation now de pends upon whether the trunk line withwhich the line switch wipers are associated "is busy or is not busy. Ifthe trunk line is busy, there will be a ground potential upon the testcontact with which the test wiper 26 is in engagement, the switchingrelay 14 will be short circuited, and the stepping magnet 16, ,whlchinterrupts its own circuit,

- will be operated in the manner of a buzzer to advance the switchwipers in search of an idle trunk line. We may assume, in the presentcase, that when the call is initiated the wipers are advanced to theidle trunk terminating in bank contacts 28-30, inclusive. When thewipers arrive at this set of contacts the short circuit is removed fromthe switching relay 14 and the operation of the stepping magnet 16 willcease because of. the high resistance of the said switching relay. Thelatter relay, however, is energized and grounds the test wiper 26 at itsarmature 18, and at its armatures 17 and 19' disconnects the lineconductors 11 and 12 from the winding of the line relay 15 and fromground, respectively, and extends them by way of wipers 25 and 27, andbank contacts 28 and 30 to the line relay (not shown) of the firstselector D. The line and release relays of the selector D are nowenergized in the usual manner and the latter relay grounds the releasetrunk conductor of the trunk line in order to establish a holdingcircuit for the switching relay 14 of the line switch C. This operationis well understood and need not be explained further.

The calling subscriber may now operate his calling device in accordancewith the first digit in the-desired number. In response to theinterruptions in the line thus produced, the vertical magnet of theselector D isoperated under control of the l ne relay to raise thewipers 40-42, inclusive, to the particular level 1n: which-areterminated the trunk lines extending to the desired group of connectorswitches. Thereafter the rotary or trunk selecting movement is initiatedautomatically in the usual manner, and the wipers are rotated in searchof an idle trunk line. Assuming that the trunk line shown in the drawingis the first idle trunk line, then when the wipers arrive at bankcontacts 43-45, inclusive, the test wiper 41 will find no groundpotential upon the test contact 44, and the rotation of the switch willcease. When this occurs. the incoming line conductors are extended inthe usual manner by way of the switch wipers 40 and 42, bank contacts 43and 45, and contact springs controlled by the reversing relay 50 to thewindings of the double wound line relay 51 of the connector E.

When the line is extended as above described, the line relay 51 isenergized over the line circu t toclose a circuit for the slow torelease release relay 52. Upon energizing, relay 52 prepares a circuitfor the vertica] magnet 58 at its armature 67, and at its armature 65connects ground to the release trunk conductor 47, thereby completing aholding circuit for the selector D and the line switch C in the wellknown manner. The calling subscriber may now operate his callingdevicein accordance with the next digit in the desired number. As aresult, the line relay 51 is deenergized a plurality of times, and atthe first deenergization transmits a current impulse to the verticalmagnet 58 over the following circuit: grounded armature 64 and itsresting contact, armature 67'and its working contact, off normal springs61 and. 63, Winding of the slow to release series relay 53, and thewinding of the vertical magnet 58 to battery. By the operation of thevertical magnet, the wipers 90-92, inclusive, are raised step by stepuntil they stand opposite the level in which is terminated the lineincluding substation A. The slow to release series relay 53 is energizedin series with the vertical magnet and by means of its armature 68maintains the circuit of the vertical magnet intact after the ofi'normal springs have been shifted, which occurs on the first verticalstep. At the end 53 is deenergized and transfers the operating" circuitto the rotary magnet 59.

The subscriber will now operate his calling device in accordance withthe next'digit of the desired number, which is the last digit which hasto do with the line selection. W'hen the calling device is operated, theline relay 51 responds as before and sends 1mpulses to the rotary magnet59 over the following circuit: grounded armature 64 and its restingcontact, armature 67 and its work- 'ing contact, off normal springs 61and 62, armature 68 and its resting contact, resting contact andarmature 75, armature 85 and its resting contact, and the winding of therotary magnet 59 to battery. By the operation of the rotary magnet, thewipers 90-92, inclusive, are rotated step by step and are finallybrought to rest in engagement with the bank contacts in which the lineincluding .substation A is terminated, these bank contacts beingindicated in the drawing by the reference characters 93, 94 and 95. Theslow to release relay 56 is energized in multiple with the rotary magnetand retains its armature attracted throughout the rotary movement of theswitch. At its armature 7 8, relay 56 connects the test wiper 91 withthe test relay 55, and at its armature 79 the said relay 56 closes ashunt around the contact at armature 75 of the test relay. The latter.operation is toprevent the test relay from opening the rotary magnetcircuit while the test wiper is pass ng over busy test contacts.

It will be assumed first that the called line is busy. Such being thecase, when the test wiper 91 arrives at test contact 94, it will find aground potential thereon, the test relay 55 will be energized, and'whenthe slow to release relay 56deenergizes at the end of the rotarymovement of the switch, the test relay 55 establishes a locking circuitfor itself at its armature'7 4. Relay 55 also opens the rotary magnetcircuit at its armature 75, thus rendering the impulse circuitineffective at this time in case the calling subscriber dials the lastor frequency selecting digit. Relay 55 also at its armature 77, connectsa lead from the busy signalling machine to the lower heavy talkingconductor. By this latter operation, an audible signal is transmitted tothe calling subscriber, and, being advised thereby that the called lineis inaccessible for the time being, he will hang up his receiver.

Having explained the operation which takes place when the called line isbusy, it will now be assumed that the line is idle when called. Underthese circumstances, when the test wiper 91 arrives at test contact 94,it will find no ground potential and the test relay 55 will not beenergized. Then when the slow to release relay 56 deenergizes at the endofthe rotary movementof the switch, a circuit is completedfor the slowacting switchin relay 57 as follows: from way of armature 74 auditsresting contact, lower winding of the switching relay 57, restingcontact and armature 78, test wiper 91, test contact 94, winding of theswitching relay 114, and the winding of the stepping magnet 116 tobattery. Relays 57 and 11.4 are energized in series over the abovecircuit, and the latter relay is operated to clear the called line ofits normal battery and ground connections in the line switch C. Itshould be noted that the relay 114 is not full operated at thistime, dueto a mechanical interthe grounded re ease trunk conductor. 47 by lockingarrangement between the armature of th s relay and the armature of theslow acting line relay 115, and the wipers of the line switch C are notconnected up. In the connector E, when the switching relay 57 isenergized, it establishes a locking circuit for itself at its armature84, grounds the test wiper 91 at armature 83, transfers the impulsngcircuit from magnet 59 to the stepping magnet 120 of the frequencyselecting switch F at its armature 85, and prepares a circuit at itsarmature 86 which provides for transmitting a tone signal to the callingsubscriber during the ringing operation.

The calling subscriber may now operate his fcalling device in accordancewith the final digit in the number, which is the digit which selects theproper frequency of ringing current for signalling the particularstation wanted. The substations A A, inelusive, have been numbered forconvenience in accordance with the digits to which they correspond. andsince the substation A is the wanted substation in the present case, thefinal digit to be called will be the digit 0. When the calling device isoperated for this digit, the line relay 51 transmits ten impulses ofcurrent to the stepping magnet 120 of the frequency selector F over thefollowing circuit: from grounded armature 64 and its resting contact,armature 67 and its working contact, ofi' normal springs 61 and 62,armature 68 and its resting contact, resting contact and armature 75,armature 85 and its working contact, and the winding of the steppingmagnet 120 to battery" By the operation of magnet 120, wipers 122 and123 are given a step by step movement and are finally brought to rest inengagement with the tenth contact in their respective banks. The slow torelease relay 56 is energized in multiple with the magnet 120 and nowserves to prevent the energization of relay 55 by holding open itsenergizing circuit at armature 80, which circuit will be explainedhereinafter. At the end of the series of impulses transmitted to themagnet 120, relay 56 is deenergized and a circuit is completed for relay55 as follows: grounded spring 124 and its working contact, which closeon the first rotary step of the frequency selector, resting contact andarmature 80, and the Winding of busy relay 55, now acting as a frequencyswitch control rela to battery. Relay 55, upon energizing, c oses theusual busy. signalling circuit at armature 77, but this is of no effectbecause the circuit has alread been opened at armature 86 of switchingre a 57. In addition, relay breaks the circuit of the stepping magnet120 at armature 75, prepares a circuit for the release magnet 121 atarmature 73, closes a circuit for the ring back tone at armature 77, andat armature.

76 com letes the signalling circuit as follows: rom the groundedgenerator Gen, through the contacts of the ringing interrupter,conductor 130, tenth contact in the bank associated with wiper 122,wiper 122, conductor 137, armature 76 and its working contact, restingcontact and armature 71, working contact and armature 87, wiper 92, bankcontact 95, conductor 102, the normally closed switch-hook contact atsubstation A,

' and the ringer at the said substation to ground. The above circuit isintermittently opened and closed by the operation of the ringinginterrupter and the ringer at substation A is thus operated at intervalsto signal the called subscriber. It is under stood, of course, that theringing current also flows through the ringers at substations A-inclusive, to ground at the same time, but the ringers at these othersubstations are tuned so that they will not respond to the frequency ofringing current which is now in use. This is according to the well knownpractice of harmonic signalling, and it follows that the ringer'atsubstation A is the only one which is operated. When the calledsubscriber at substation A removes his receiver to answer the call, theringer thereat is disconnected and the ringing circuit is completed overa metallic circuit including the other line conductor 101 and the lowerwinding of the ring cut-oif relay 54 at the connector E, which may betraced as follows: grounded armature 66 and its working contact, lowerwinding of ring cut-off relay 54, contacts 15, inclusive, of left handbank of switch F, conductor 135, contact 10 of right hand bank, wiper123, conductor 136, working contact and armature 72, resting contact andarmature 69, working contact and armature 81, wiper 90, bank contact 93,line conductor 101, substation equipment, line conductor 102, bankcontact 95, wiper 92, armature 87 and its working contact, armature 71and its resting contact, Working contact and armature 76, Wiper 122,contact 10 of left hand bank, conductor 130, and through the contact ofthe ringing interrupter to direct battery or to battery by way ofgenerator Gen. The ring cut-off relay 54 is now energized andestablishes a locking circuit for itself at armature (70, opens theringing circuit at its armatures 69 and 71, opens the ring back tonecircuit at the latter armature, and at the working contacts of thesesame armatures finally completes the talking circuit.

The required connection has now been established and the calling andcalled subscribers may converse as desired. Current for the transmitterat substation A is supplied through the windings of the double woundline relay 51, while current for the transmitter at substation A issupplied placed at substation A the line and release relays 51 and 52are deenergized and the latter relay closes a circuit for the releasemagnet 60, which operates to restore the connector E to normal positionin the usual manner. Relay 52 also disconnects ground from the releasetrunk conductor 47, thereby breaking the holding circuits of theselector D and line switch C, and these two switches are accordinglyrestored to normal also. At the same time that relay 52 closes thecircuit of release magnet 60, the said relay closes a circuit atarmature by way of armature 73 of relay 55 which includes the releasemagnet 121 of the frequency selecting switch F. By the operation of therelease magnet 121, the wipers are restored to normal osition. Thus allthe apparatus in use has een freed and made ready for use in anotherconnection.

A brief explanation will now be given of the manner in which the otherstations of the line are signalled. Substations A, A, A and A, may bereached by calling digits 6, 7, 8, and 9, respectively, as the finaldigits,

and the operations are exactly the same as when substation A is called,except that a different frequency of ringing current is selected. Itwill be understood in this connection that conductors 130434, inclusive,all extend to separate ringing current generators, and these generatorsare all'of diiferent frequencies. Although only one of these generatorsis shown on the drawing, it is believed that this explanation will makethe arrangement perfectly clear. The ringers at the five substationsjust referred to are all connected from the line conductor 102 toground. In order tooperate the ringers at the remaining substations A A,inclusive,

which are connectedfrom the line conductor 101 to ground, digits 1, 2,3,34, and 5, respectively, must be called as the final digits. Suppose,for example, that it is desired to call the substation A, the ringer atwhich station is tuned to the same frequency as the ringer at substationA. The final digit to be called in this case is the digit 5, and

the wipers of the frequency selector I? are advanced five steps intoengagement with the fifth contact in their respective banks. When thewiper 123 comes to rest on the fifth contact, the ringing generatorshown on the drawing is selected, as the first five contacts in the bankassociated with wiper 123 are connected in multiple with the last fivecontacts in thebank associated with the wiper 122. c When relay 56deenergizes at the end of the operation of the fre uency selectingswitch, a circuit is closed or the relay the same as before, and whenrelay 55 energizes, a ringing circuit is completed-substantially thesame as previously described except that in the present case, theringing current is applied to the line by way of wiper 123 of frequencyselecting switch F and connector wiper 90 instead of by way of thefrequency selecting switch wiper 122 and connector wiper 92, and henceflows over the line conductor 101 and through the ringers at substationsA inclusive, to ground. The ringer at substation A is accordinglyoperated. Substations A to A, inclusive, may be called in the samemanner by using K the final digits which correspond to thesesubstations.

Having described my invention, what I consider to be new and desire tohave protected by Letters Patent will be pointed out in the appendedclaims.

What is claimed is:

1. In a selective ringing telephone system, a party line, a connectorswitch for extending a connection to said line, a frequency selector forselecting the proper ringing current to be applied to said line, a relayin said connector for closing the ringing circuit at one point, a secondrelay energized while the frequency selector is being operated anddeenergized thereafter, ofl' normal springs on said frequency selector,a circuit o for said first relay jointly controlled by said second relayand said off normal springs, and an automatic interrupter for intermittently closing said ringing circuit at another point.

2. In a telephone system, a party line, substation ringers connectedfrom opposite sides of said line to ground, an automatic switch forextending a connection to said line, said switch including .a pair ofline wipers, a plurality of sources of ringing current of differentcharacter there being half as many of said sources as there are stationson said line, and a device assoclated with said switch for selecting oneof said sources which of said wipers the selected source is to beconnected.

3. In a telephone system, different sources of ringing current at theexchange, a party line, substation ringersiequal in number to 'thenumber of said sources connected from one side of said line to ground, alike number of ringers connected from the other side'of said line toground, means including on, the side to which the selected source isconnected depending on which of said devices is in use.

4. In a telephone system, a party line, a plurality of stations andringers thereat connected from op osite sidesof said line to ground, aplurality of different ringing current sources at the exchange less innumber than the number of said stations, an automatic connector switchat which said line terminates in a single set of bank contacts, meansfor operating said connector to connect with said contacts, a frequencyselector having two sets of bank contacts, a portion of one bank beingconnected to said current sources and multipled with a non-correspondingportion of the other bank, two wipers for then selecting one of saidcurrent sources via either bank, and a connecting device operable forconnecting the selected source to either side of said line to signaleither one of two of said stations, the station and for simultaneouslypreparing a circuit for the selected source which determines tosignalled depending upon which of the said tacts, means for operatingsaid connector to connect with said contacts, a frequency selectingswitch associated'withsaid connector at which said current sourcesterminate in a portion of one set of bank contacts and are multipledwith a non-corresponding por- ,tion of a second set of bank contacts,means for operating said frequency selecting switch to select a rmgingcurrent source via either set of bank contacts, and means to signal astation on either side of said line depending upon which of said banksis used.

6. In a telephone system, a connector switch, a line accessible thereto,a plurality of sources of ringing current, a ring outofi relay in saidconnector switch, a frequency selectin switch associated with saidconnector switc having two wipers and two sets ofbank contacts, thefirst half of one set of contacts being multipled with the second halfofthe other set and connected to said sources of ringing current, theremaining contacts being connected in multiple and extended to said ringcut-01f relay, means for impressing said ringing current sources on oneside of said line when said wipers are brought to rest on the first halfof said contacts, and for impressing said rin ing current sources on theother side of sai line when said wipers are brought to rest'on thesecond half of said contacts, and

means responsive to said wipers being brought to rest on either half ofsaid contacts for preparing a circuit for said r ng cut ofi relay.

7. In combination, an automatic connector switch and an associatedfrequency selector for connecting with and ringing on either side of. aline, said switch including a combination busy test and control relayfor erforming the usual busy test relay functions when the switchconnects with a busy line and for preparing the ringing circuit, thefrequency selector release circuit, and closing the ring-back tonecircuit when vthe switch connects with an idle line.

8. In a connector switch, a combination busy test and rin ing circuitcontrol relay, contacts on said re ay for closing a busy signallingcircuit when the connector connects with a busy line, contacts on saidrelay for closing the ringing circuit when said connector connects withan idle line, and means for energizing said relay to close said lastmentioned contacts a predetermined time afaiy connection to an-idle lineis estab- 18 e 9. In a telephone system diflferent sources I stationthereon, the side to which the selected source is connected depending onwhich of said wipers is used to select the source.

10. In a telephone system, a party line, diflerent sources of signallingcurrent, means for extending a connection to said line, and a devicecomprising two wipers used alternatively for selecting any one of saidsources to signal any desired station thereon, the

wiper used to select the source depending on the extent of operation ofsaid device.

In witness whereof, I hereunto subscribe 'my name this 13th day ofAugust, A. D.

- ARTHUR J. RAY.

